It is quite common at present in harvesters such as high capacity combines to utilize so-called floating type cutterbars which have limited flexibility for purposes of permitting the same automatically to conform to the contour of the surface of a field upon which the harvesting is being undertaken. This is for purposes of insuring relatively close cutting of the crop being harvested. In such harvesters, it also is common to employ a rotatable reel having a substantially horizontal axis and including pickup fingers, the lower portion of which is adjacent the cutterbar and the reel being operable to sweep crop material against the cutterbar and into the header.
Particularly in regard to the employment of elongated, floating cutterbars which have limited flexibility, there is a problem involved in maintaining desired spaced relationship between the reel or the fingers of the reel and the floating cutterbar, primarily because the floating cutterbar flexes to conform to the contour of the ground. In some conditions it is advantageous to keep a relatively close relationship between said reel and floating cutterbar in order to sweep material from the floating cutterbar into the auger of the header.
Because of the relative movement between the floating cutterbar and the fingers of the reel, either the axis of the reel must be kept high enough to permit the fingers of the reel to clear the cutterbar in its maximum upper position resulting from the flexing thereof and under which the reel is not able to sweep the cutterbar clean, or the reel must be run at a lower elevation relative to the cutterbar, and under such circumstances, run the risk of the fingers of the reel engaging the higher portions of the flexible cutting bar.
The present harvester art has examples of the employment of hydraulic means to control the height of a reel relative to the cutterbar of the harvester. There also is known art illustrating means to control the height of the entire header relative to the ground automatically. Examples of this are illustrated in U.S. Pat. No. 3,383,845, dated May 21, 1968, to Hirsch et al. and U.S. Pat. No. 3,886,718, dated June 3, 1975, to Talbot.
It also is known in the art to employ flexible, floating cutterbars which are adapted to operate over uneven field surfaces and the limited flexibility of the bars enabling the same to cut the harvested material to a substantially uniform height above the ground. One example of a patent illustrating such cutting bar is U.S. Pat. No. 3,982,383, dated Sept. 28, 1976, in the name of Mott.